High-frequency devices such as front end modules of video devices and communications devices utilize high-frequency circuits to obtain circuit characteristics. An upper surface of a circuit board 4 provided within a frame body 5 is divided by a plurality of partition plates 3, as shown in FIG. 4, and an opening of the frame body 5 is covered with a closure (not shown) to provide electric shield, for preventing detrimental effect resulting from the leakage of a local oscillation signal to the other circuits, or for not affecting the high-frequency circuit due to a signal transmitted by the other device.
The closure has a plurality of slit pieces 2 integrally formed therewith by cutting out a part of the closure to a raised form as shown in FIG. 5. Each of the slit pieces 2 is cut out from the closure 1 along a periphery except for a base portion and inclines toward the interior of the frame body 5. An outer end of the slit piece 2 comes into contact with an end of the partition plate 3, as shown in FIG. 6. Accordingly the closure 1 is grounded, thereby suppressing the transmission, to the other circuits, of a local oscillation signal produced from a local oscillator (not shown) disposed on the circuit board 4.
According to the prior art described, whereas the outer end of each split piece should reliably contact with the end of the partition plate for grounding, the contact pressure thereof may drop depending on dimensional tolerance of the partition plate or on that of the slit piece, or the closure is pressed due to problem involved in handling the device to drop cut-out inclination angle of the piece, deteriorating the contact pressure. This gives rise to the problem that the closure is not reliably grounded. It is, therefore, necessary to make such a contrivance as to select a metallic material having a high elasticity as a material for use in the closure integrally formed with the slit piece, and as to allow the slit piece to have a sufficient spring force by extending the slit piece as long as possible.
However, limiting the material of the closure increases the cost of the device, and extending the slit piece hampers the high-frequency device from obtaining desired characteristics because the high-frequency device needs to be grounded in the shortest distance, and further from making the device compact.
An object of the present invention is to provide improving technique for ensuring and stabilizing the contact between the slit piece and the partition plate, and providing reliable grounding.